Solving the Galvanic Cell Problem in Ferro-Cement
Interim technical rept.
CALIFORNIA UNIV BERKELEY DIV OF STRUCTURAL ENGINEERING AND STRUCTURAL MECHANICS
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The nature and constitution of ferro-cement is reviewed with special reference to the structure of cement paste. The microstructure of low water to- cement ratio pastes is presented in schematic illustrations to show that a thin paste layer can be used to protect steel reinforcing material from a marine environment. A galvanic cell between the plain steel reinforcing bar and the galvanized steel mesh ordinarily used in ferro-cement is identified. This galvanic cell gives off hydrogen gas at the plain steel reinforcing bar which leads to poor bonding. Possible solutions to this problem are presented and one, the use of chromium trioxide CrO3 in the mix water, is shown to solve the problem most effectively. This leads to improved mechanical properties as well as a sounder barrier to corrosion of the reinforcement.
- Physical Chemistry
- Construction Equipment, Materials and Supplies